title: Fine tuning of reactive oxygen species homeostasis regulates primed immune responses in Arabidopsis.
abstract: Selected stimuli can prime the plant immune system for a faster and stronger defense reaction to pathogen attack. Pretreatment of Arabidopsis with the chemical agent β-aminobutyric acid (BABA) augmented H2O2 and callose production after induction with the pathogen-associated molecular pattern (PAMP) chitosan, or inoculation with the necrotrophic fungus Plectosphaerella cucumerina. However, BABA failed to prime H2O2 and callose production after challenge with the bacterial PAMP Flg22. Analysis of Arabidopsis mutants in reactive oxygen species (ROS) production (rbohD) or ROS scavenging (pad2, vtc1, and cat2) suggested a regulatory role for ROS homeostasis in priming of chitosan- and P. cucumerina-inducible callose and ROS. Moreover, rbohD and pad2 were both impaired in BABA-induced resistance against P. cucumerina. Gene expression analysis revealed direct induction of NADPH/respiratory burst oxidase protein D (RBOHD), γ-glutamylcysteine synthetase 1 (GSH1), and vitamin C defective 1 (VTC1) genes after BABA treatment. Conversely, ascorbate peroxidase 1 (APX1) transcription was repressed by BABA after challenge with chitosan or P. cucumerina, probably to provide a more oxidized environment in the cell and facilitate augmented ROS accumulation. Measuring ratios between reduced and oxidized glutathione confirmed that augmented defense expression in primed plants is associated with a more oxidized cellular status. Together, our data indicate that an altered ROS equilibrium is required for augmented defense expression in primed plants.
authors.forename: Victoria
authors.initials: V
authors.lastname: Pastor
authors.forename: Estrella
authors.initials: E
authors.lastname: Luna
authors.forename: Jurriaan
authors.initials: J
authors.lastname: Ton
authors.forename: Miguel
authors.initials: M
authors.lastname: Cerezo
authors.forename: Pilar
authors.initials: P
authors.lastname: García-Agustín
authors.forename: Victor
authors.initials: V
authors.lastname: Flors
mesh_terms: D000613:Aminobutyrates / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000276:immunology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001203:Ascomycota / Q000502:physiology*; D060387:Ascorbate Peroxidases / Q000235:genetics / Q000378:metabolism; D048271:Chitosan / Q000494:pharmacology; D004151:Dipeptides / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005936:Glucans / Q000378:metabolism; D005721:Glutamate-Cysteine Ligase / Q000235:genetics / Q000378:metabolism; D006706:Homeostasis; D006861:Hydrogen Peroxide / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D057865:Plant Immunity; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D000613:Aminobutyrates; D029681:Arabidopsis Proteins; D004151:Dipeptides; D005936:Glucans; D017382:Reactive Oxygen Species; C047667:3-aminobutyric acid; D048271:Chitosan; C048306:callose; D006861:Hydrogen Peroxide; C555290:APX1 protein, Arabidopsis; D060387:Ascorbate Peroxidases; C568857:AT5G47910 protein, Arabidopsis; D019255:NADPH Oxidases; D005721:Glutamate-Cysteine Ligase; C493655:Gsh1 protein, Arabidopsis; C017341:gamma-glutamylcysteine